Physicians currently utilize a variety of techniques to control elongate surgical tools and devices such as catheters. As a catheter, endoscope, or other medical device is advanced ever deeper into tortuous confines of a patient's vasculature, the device becomes correspondingly more difficult to control. Although real-time x-ray imaging can provide guidance to an operating physician during such a procedure, over time the physician runs the risk of repeatedly being exposed to x-ray fields if he or she remains in the vicinity of the patient while x-rays are being projected.
In many applications, magnetic fields can be used to steer the tip of a catheter or other surgical tool. Magnetic steering techniques provide precise, computer-assisted control of a catheter tip and allow an operating physician to remain outside the x-ray imaging field while steering a catheter tip. Nevertheless, during some medical procedures such as cardiac mapping, the physician may find it preferable to advance or retract the catheter by mechanical means. During cardiac mapping, a catheter is repeatedly advanced and retracted within a patient's heart while a tip of the catheter is redirected to different locations on the heart wall.
Although systems have been developed that would automatically advance and/or retract elongate medical devices, the object of such systems has been to provide the capability for retracting, rather than advancing, a medical device within a patient. For example, systems are in use that collect imaging information generated by a rotating imaging device as the device is retracted from the vasculature of a patient. If such a system were to be used to advance a medical device in a patient during a medical procedure, perforation and injury to the patient could result, particularly when the medical device has a stiff distal tip. A physician might choose to use an automatic retractor in order to reduce time and fatigue during a medical procedure. However, when the physician must be present in the operating field to manually control advancement of a device, the physician still faces repeated x-ray exposure. Thus it would be desirable to provide a way for physicians to mechanically advance and retract medical devices while outside the x-ray field.